How Many Grams in an Ounce of Gold?

1 Troy ounce (used for gold) equals exactly

31,1035 grams

The Troy Ounce: Different from the Common Ounce

When talking about gold, silver, and other precious metals, the reference unit is not the common (avoirdupois) ounce used for food and everyday items, equal to 28.35 grams, but the Troy ounce, a different and slightly heavier unit, exactly equal to 31.1034768 grams. This distinction is essential for those following the gold financial market: the price of gold quoted 'per ounce' always refers to the Troy ounce.

The Conversion Formula

To convert a measurement from Troy ounces to grams, simply multiply the value in Troy ounces by 31.1035:

grams = Troy ounces × 31.1035

To convert from grams to Troy ounces, perform the inverse operation, dividing by 31.1035:

Troy ounces = grams ÷ 31.1035

Practical Examples

  • 1 Troy oz = 31.1035 g (weight of a classic gold bullion coin)
  • 5 Troy oz ≈ 155.52 g
  • 10 Troy oz ≈ 311.03 g
  • Difference from the common ounce: 1 Troy oz (31.10 g) ≈ 1.097 avoirdupois ounces (28.35 g each)

Why Knowing the Troy Ounce Matters

The Troy ounce is used exclusively for precious metals (gold, silver, platinum) in international financial markets. Knowing the difference from the common ounce avoids significant calculation errors for those investing in physical gold, following precious metal quotes, or buying jewelry and bullion, where even a small weight inaccuracy can translate into a considerable difference in value.

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